Field
This disclosure relates generally to semiconductor memory devices, and more specifically, to static random access memory (SRAM) with backup non-volatile memory that includes magnetic tunneling junction (MTJ) resistive elements.
Related Art
Memories with resistive storage elements under development across the semiconductor industry are geared to replace conventional random access memory (RAM) and non-volatile memory devices. The resistive memory devices include magnetoresistive random access memory (MRAM), Resistive random-access memory (RRAM or ReRAM), and phase-change memory (PCM), among others. Most of the resistive memory devices are implemented in one transistor/one resistive element or one diode/one resistive element memory cell configurations, which require minimal cell area but exhibit relatively slow read and write performance (e.g., approximately 30 nanoseconds or more per operation). Thus, resistive memory devices are not a viable substitute for much of the static RAM in a higher performance system where read/write operations occur within a few clock cycles. It is also difficult to produce a reliable one transistor/one resistive element or one diode/one resistive element memory.
Memory cells with one transistor and one resistive element may eventually replace embedded flash on future SoCs, but it is desirable to use these same elements to replace the static random access memory (SRAM) as well. Potentially, less flash would be needed, or the system could use a more efficient architecture, if the ‘fast’ memory such as SRAM was also compact and non-volatile.